GNU bug report logs -
#67536
29.1; Calc mode's math-read-preprocess-string conses unnecessarily
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Reported by: Raffael Stocker <r.stocker <at> mnet-mail.de>
Date: Wed, 29 Nov 2023 21:32:02 UTC
Severity: normal
Found in version 29.1
Done: Mattias Engdegård <mattias.engdegard <at> gmail.com>
Bug is archived. No further changes may be made.
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Your bug report
#67536: 29.1; Calc mode's math-read-preprocess-string conses unnecessarily
which was filed against the emacs package, has been closed.
The explanation is attached below, along with your original report.
If you require more details, please reply to 67536 <at> debbugs.gnu.org.
--
67536: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=67536
GNU Bug Tracking System
Contact help-debbugs <at> gnu.org with problems
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19 dec. 2023 kl. 18.09 skrev Raffael Stocker <r.stocker <at> mnet-mail.de>:
> Yes, I think this will be fine. Thanks!
Closing.
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Org table re-calculation is very slow, partly due to
math-read-preprocess-string of calc mode consing unnecessarily. For
example, in one (large) table, I get the following memory usage from the
profiler:
...
60,252,646 96% - org-ctrl-c-ctrl-c
60,248,166 96% - org-table-calc-current-TBLFM
60,216,431 96% - funcall-interactively
60,205,119 96% - org-table-recalculate
49,094,651 78% - org-table-eval-formula
32,624,631 52% - calc-eval
32,624,631 52% - calc-do-calc-eval
32,620,487 52% - calc-do-calc-eval
32,611,151 52% - math-read-exprs
29,388,838 47% + math-read-preprocess-string
2,343,257 3% + math-read-expr-list
...
The reason for the slow-down seems to be that
math-read-preprocess-string conses a lot, keeping the GC busy. This is
due to heavy use of replace-regexp-in-string in this function:
(defun math-read-preprocess-string (str)
"Replace some substrings of STR by Calc equivalents."
(setq str
(replace-regexp-in-string (concat "[" math-read-superscripts "]+")
"^(\\&)" str))
(setq str
(replace-regexp-in-string (concat "[" math-read-subscripts "]+")
"_(\\&)" str))
(let ((rep-list math-read-replacement-list))
(while rep-list
;; consing like a mad-man here:
(setq str
(replace-regexp-in-string (nth 0 (car rep-list))
(nth 1 (car rep-list)) str))
(setq rep-list (cdr rep-list))))
str)
I would like to propose using a temp buffer instead of kneading the
string into submission:
(defun math-read-preprocess-string (str)
"Replace some substrings of STR by Calc equivalents."
(with-temp-buffer
(insert str)
(goto-char 0)
(while (re-search-forward (concat "[" math-read-superscripts "]+") nil t)
(replace-match "^(\\&)"))
(goto-char 0)
(while (re-search-forward (concat "[" math-read-subscripts "]+") nil t)
(replace-match "_(\\&)"))
(goto-char 0)
(let ((rep-list math-read-replacement-list))
(while rep-list
(while (re-search-forward (nth 0 (car rep-list)) nil t)
(replace-match (nth 1 (car rep-list))))
(goto-char 0)
(setq rep-list (cdr rep-list))))
(buffer-string)))
With this replacement, the profiler shows much less memory usage on the
same org table:
...
30,411,804 91% - org-ctrl-c-ctrl-c
30,407,324 91% - org-table-calc-current-TBLFM
30,363,932 91% - funcall-interactively
30,331,900 91% - org-table-recalculate
20,430,223 61% - org-table-eval-formula
6,751,852 20% + org-table-justify-field-maybe
4,598,523 13% - calc-eval
4,586,091 13% - calc-do-calc-eval
4,569,619 13% - calc-do-calc-eval
4,547,971 13% - math-read-exprs
2,297,453 6% + math-read-expr-list
1,347,377 4% + math-read-preprocess-string
7,296 0% math-read-token
...
Only I am not sure the replacement is correct in all possible edge cases
(or whether it uses so much less memory because I have overlooked
something).
What do you think? Can a calc-mode expert weigh in here?
Regards,
Raffael
This bug report was last modified 1 year and 155 days ago.
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